A polystyrene board with flame retardant properties and its preparation method and application

Abstract

The present invention belongs to the technical field of building materials, and specifically discloses a polystyrene board with flame retardant properties, and a preparation method and application thereof. The polystyrene board with flame retardant properties provided by the present invention comprises components: expandable polystyrene, thermosetting resin, curing agent, organic modified montmorillonite and coating material; the coating material comprises diatomaceous earth-based flame retardant, silica aerogel and nanocellulose; the diatomaceous earth-based flame retardant is gemini quaternary ammonium salt modified diatomaceous earth. On the premise of meeting the mechanical strength, the polystyrene board provided by the present invention has a lower thermal conductivity and excellent fire resistance, which can reach the fire resistance Class A standard. The present invention also provides a preparation method of the above-mentioned polystyrene board with flame retardant properties, and the preparation method has the advantages of simple process, easy availability of raw materials, safe operation, and easy promotion and application. The present invention can be used in the field of preparation of building walls or wall materials.

Description

Technical Field

[0001] The invention belongs to the field of building materials, and in particular relates to a polystyrene board with flame retardancy and a preparation method and application thereof. Background Art

[0002] The implementation of building energy-saving policies and building fire protection regulations has promoted the rapid development of wall flame retardant materials. With the enhancement of people's awareness of fire prevention, fire disasters have received increasing attention. Therefore, people have higher and higher requirements for the flame retardant properties of walls.

[0003] As one of the five general synthetic resins, polystyrene (PS) has main products such as GPPS, EPS, HIPS and ABS, and its output is second only to polyethylene (PE), polyvinyl chloride (PVC) and polypropylene (PP). Since polystyrene board is a thermal insulation material with excellent properties such as high pressure resistance, low water absorption, moisture resistance, airtightness, light weight, corrosion resistance, anti-aging, and low thermal conductivity, it is now widely used in building walls, roof insulation, and insulation layers of composite insulation boards. However, PS is very easy to burn, while releasing a large amount of harmful smoke, accompanied by melting, and is very likely to cause secondary fires. With the enhancement of people's awareness of fire prevention, fire disasters are increasingly valued by people. Although adding flame retardants in the prior art can improve the flame retardancy of polystyrene materials, the flame retardancy of most polystyrene materials can only reach Class B, and few reach Class A. Therefore, the present invention proposes a polystyrene board with flame retardant properties that is adapted to the current building energy-saving design standard requirements and fire protection specifications, and a preparation method thereof, as well as the application of the polystyrene board in a building wall with flame retardant properties. Summary of the invention

[0004] The object of the present invention is to provide a polystyrene board with flame retardant properties, which can achieve Class A fire resistance while meeting specific index requirements.

[0005] The second object of the present invention is to provide a method for preparing the polystyrene board having flame retardant properties, and to provide a production scheme suitable for promotion for the preparation of the polystyrene board.

[0006] The third object of the present invention is to provide the application of the above-mentioned polystyrene board with flame retardant properties, so as to provide more choices for the selection of flame retardant building walls.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] In a first aspect, the present invention provides a polystyrene board with flame retardant properties, comprising the following components in parts by weight: 90 to 100 parts of expandable polystyrene, 50 to 60 parts of thermosetting resin, 1.2 to 2.2 parts of curing agent, 2 to 4 parts of organic modified montmorillonite and 30 to 40 parts of coating material;

[0009] The coating material includes a diatomaceous earth-based flame retardant, silica aerogel and nanocellulose;

[0010] Wherein, the diatomaceous earth-based flame retardant is diatomaceous earth modified by gemini quaternary ammonium salt;

[0011] The structural formula of the gemini quaternary ammonium salt is:

[0012] .

[0013] The present invention prepares gemini quaternary ammonium salt by quaternization reaction of 1,5-dibromopentane and triethylamine, and then prepares gemini quaternary ammonium salt modified diatomite by reacting the gemini quaternary ammonium salt with diatomite. The gemini quaternary ammonium salt is adsorbed on the surface of diatomite to form a cationic protective film, which improves the hydrophobicity of diatomite and further improves the flame retardant effect of the flame retardant. Compared with conventional montmorillonite, organic modified montmorillonite has better compatibility with organic matter and has a significant flame retardant effect on organic polymers; the organic modified montmorillonite added in the present invention has good compatibility with polystyrene, and the organic modified montmorillonite can effectively promote the carbonization of polystyrene and prevent further combustion of the matrix. Silica aerogel has the characteristics of large specific surface area, high porosity, low density, low thermal conductivity, etc., but its mechanical strength is low, so the present invention adds nanocellulose to the coating material to improve the mechanical strength of silica aerogel. The present invention adds organic modified montmorillonite and applies a coating layer containing a diatomaceous earth-based flame retardant, silica aerogel and nanocellulose. The four cooperate to enable the polystyrene board prepared by the present invention to have the characteristics of low thermal conductivity and high flame retardancy while meeting the mechanical properties. The obtained polystyrene board can reach the fire resistance Class A standard.

[0014] Preferably, 1,5-dibromopentane and triethylamine are subjected to a quaternization reaction at 81° C. to 85° C. for 5 h to 6 h to obtain the gemini quaternary ammonium salt; the mass ratio of 1,5-dibromopentane to triethylamine is 0.99:1 to 1.14:1, that is, the molar ratio is 1:2.0 to 2.3.

[0015] Preferably, the mass ratio of the diatomaceous earth-based flame retardant, the silica aerogel and the nanocellulose in the coating material is 3-4:6-12:0.2-0.4.

[0016] Preferably, the preparation method of the gemini quaternary ammonium salt modified diatomite comprises the following steps: mixing a diatomite suspension with a gemini quaternary ammonium salt solution to obtain a mixed suspension, reacting at 81° C. to 85° C. for 3 h to 4 h to obtain the gemini quaternary ammonium salt modified diatomite;

[0017] Wherein, the mass ratio of the gemini quaternary ammonium salt to diatomaceous earth in the mixed suspension is 1.0:3-1.4:3;

[0018] The mass concentration of the diatomite suspension is 40g / L to 60g / L;

[0019] The mass concentration of the gemini quaternary ammonium salt solution is 40g / L~60g / L.

[0020] Preferably, the organic modified montmorillonite includes at least one of hexadecyltrimethylammonium bromide modified montmorillonite or silane modified montmorillonite; and the silica aerogel is micron-sized silica aerogel.

[0021] Montmorillonite is a commonly used modifier for polymers. It is mainly found in bentonite ore and is composed of hydroaluminosilicate. It has high specific heat capacity, good adsorption, barrier properties, flame retardancy and thermal stability. However, montmorillonite is hydrophilic and oleophobic and is very easy to agglomerate. In order to improve the compatibility of montmorillonite with polymer matrix, it is often modified organically. The basic structural unit of montmorillonite is a layered structure formed by a piece of aluminum oxide octahedron sandwiched between two pieces of silicon oxide tetrahedron, which is formed by sharing oxygen atoms. Na is often adsorbed between the layers. + , K + Mg 2+ and Ca 2+ The cations generated by the ionization of hexadecyltrimethylammonium bromide in water can exchange with the cations between the montmorillonite layers, thereby allowing the hexadecyltrimethylammonium bromide to intercalate into the montmorillonite layers.

[0022] The flame retardant mechanism of polystyrene is generally based on condensed phase flame retardancy. When the polystyrene board provided by the present invention is heated, hexadecyltrimethylammonium bromide first undergoes thermal decomposition. On the one hand, the decomposition product olefin reacts with oxygen in the air to generate water or non-flammable gas, absorbing a large amount of heat; on the other hand, strong acid catalytic reaction points are generated on the surface of the montmorillonite after thermal decomposition of the modifier, increasing the carbon precursor structure, which can promote the carbonization of polystyrene. At the same time, the organic modified montmorillonite and the gemini quaternary ammonium salt modified diatomaceous earth cooperate to increase the density of the carbon layer, thereby improving the flame retardant performance of polystyrene.

[0023] The preparation method of hexadecyltrimethylammonium bromide modified montmorillonite in the present application is as follows: add 15g of montmorillonite to 400g of water, stir at 70°C~80°C for 4h~5h, add 8g of hexadecyltrimethylammonium bromide, continue to stir at constant temperature for 3.5h, take out after natural cooling, centrifuge, wash with 60% ethanol solution until the supernatant is neutral, vacuum dry, grind, and pass through a 300-mesh sieve to obtain hexadecyltrimethylammonium bromide modified montmorillonite.

[0024] Aerogel refers to a solid material that is composed of continuous nanoparticles or polymer molecules that aggregate to form a nanoporous network structure, and the nanopores are filled with a gaseous dispersion medium. Silica aerogel is a lightweight porous non-metallic material composed of SiO2 particles with a three-dimensional nano-network structure. It has a low density, a porosity of more than 90%, an ultra-high specific surface area, and even a lower thermal conductivity than air. Therefore, it has a wide range of applications in thermal insulation, environmental purification, and life medicine. However, silica aerogel has the disadvantage of low mechanical strength, so its application in the field of materials with specific compressive strength requirements is limited.

[0025] The silica aerogel selected in the present invention is micron-sized, has a SiO2 content (dry basis) of ≥99%, an average particle size of 5.0-15.0 μm, and a pH (5% aqueous suspension) of 6.0-7.0.

[0026] The fiber diameter of the nanocellulose selected by the present invention is 3-5 nm, the fiber length is 500-1000 nm, and the pH is 7-8.

[0027] Preferably, the thermosetting resin is compounded from phenolic resin and epoxy resin in a mass ratio of 6:1 to 4:1. It should be understood that the embodiments of the present invention are described by taking only individual resins as examples, and other types or models of resin products may also be applied according to the common knowledge of those skilled in the art.

[0028] Preferably, the curing agent includes at least one of phosphoric acid, sulfuric acid, phthalic anhydride or maleic anhydride.

[0029] Preferably, the fire resistance grade of the polystyrene board having flame retardant properties is A grade.

[0030] In a second aspect, the present invention provides a method for preparing the polystyrene board having flame retardancy, the method comprising the following steps:

[0031] Step 1, pre-expanding expandable polystyrene to obtain pre-expanded granular material;

[0032] Step 2: Add the thermosetting resin and curing agent to the pre-expanded granules and mix them evenly, then add the organic modified montmorillonite and coating material in sequence to obtain pre-expanded granules with modified montmorillonite and coating material coated on the surface, and perform compression molding to obtain the polystyrene board with flame retardant properties.

[0033] The preparation method provided by the present invention has the advantages of simple preparation process, no need to add expensive equipment on the basis of conventional preparation equipment, easy availability of raw materials, safe operation, easy promotion and application, etc.

[0034] In a third aspect, the present invention also provides the use of the above-mentioned polystyrene board with flame retardant properties in building walls.

[0035] Since the polystyrene board with flame retardancy provided by the present invention has excellent flame retardancy, it can be widely used in the direction of building walls. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] The silica aerogel selected by the present invention has a SiO2 content (dry basis) of ≥99%, an average particle size of 5.0-15.0 μm, and a pH (5% aqueous suspension) of 6.0-7.0.

[0038] The fiber diameter of the nanocellulose selected by the present invention is 3-5 nm, the fiber length is 500-1000 nm, and the pH is 7-8.

[0039] Example 1

[0040] This embodiment provides a polystyrene board with flame retardant properties, which includes the following components in parts by weight: 90 parts of expandable polystyrene, 50 parts of thermosetting resin, 1.2 parts of maleic anhydride, 2 parts of hexadecyltrimethylammonium bromide modified montmorillonite and 30 parts of coating material;

[0041] The coating material is compounded by a diatomaceous earth-based flame retardant, silica aerogel and nanocellulose in a mass ratio of 3:12:0.4; the average particle size of the silica aerogel is 5.0 μm;

[0042] Wherein, the diatomaceous earth-based flame retardant is diatomaceous earth modified by gemini quaternary ammonium salt;

[0043] The thermosetting resin is compounded by phenolic resin and epoxy resin in a mass ratio of 4:1.

[0044] The preparation method of the diatomaceous earth-based flame retardant comprises the following steps:

[0045] Step A, preparation of gemini quaternary ammonium salt

[0046] In a three-necked flask equipped with a reflux condenser, a certain amount of anhydrous ethanol was added, triethylamine and 1,5-dibromopentane were added in a mass ratio of 0.99:1 (molar ratio of 2:1), and a quaternization reaction was carried out at 81°C for 6 hours; magnetic stirring was performed during the quaternization reaction at a stirring speed of 150rpm. After the quaternization reaction, the mixture was cooled to room temperature to obtain a colorless transparent liquid, and the solvent was removed by reduced pressure distillation at 60°C; then the mixture was rinsed three times with ethyl acetate and acetone in a volume ratio of 1:1, and a white solid was obtained by suction filtration, which was vacuum dried at 50°C to obtain the target product;

[0047] The above target product contains quaternary ammonium salt N + The characteristic peaks of tertiary amine indicate that the tertiary amine has undergone quaternization reaction; that is, the target product obtained is a gemini quaternary ammonium salt, and its structural formula is: .

[0048] Step B: Preparation of Gemini Quaternary Ammonium Salt Modified Diatomaceous Earth

[0049] The diatomite and deionized water were mixed, heated in a water bath at 80°C and mechanically stirred until uniformly dispersed, to obtain a diatomite suspension with a mass concentration of 40 g / L. The above-prepared gemini quaternary ammonium salt and deionized water were weighed, and fully stirred until completely dissolved to obtain a gemini quaternary ammonium salt solution with a mass concentration of 40 g / L. The above gemini quaternary ammonium salt solution was mixed with the diatomite suspension to obtain a mixed suspension, mechanically stirred at 81°C for 4 hours, and then the mixed suspension was centrifuged and washed 3 times with deionized water, placed in a drying oven and dried at 80°C to constant weight, and ground to 300 meshes to obtain gemini quaternary ammonium salt modified diatomite.

[0050] Wherein, the mass ratio of the gemini quaternary ammonium salt to diatomaceous earth in the mixed suspension is 1:3.

[0051] In this embodiment, the phenolic resin selected is SP1068 phenolic resin; the epoxy resin selected is DER6508 epoxy resin;

[0052] This embodiment also provides a method for preparing the polystyrene board having flame retardancy, and the preparation method comprises the following steps:

[0053] Step 1: Pre-expand expandable polystyrene with steam to obtain a density of 20 kg / m 3 Pre-fermented pellets;

[0054] Step 2: Add thermosetting resin and maleic anhydride to the pre-expanded granules and mix evenly, then mix at 90°C for 30 minutes, add hexadecyltrimethylammonium bromide modified montmorillonite and mix evenly, then add the coating material to obtain the pre-expanded granules with the surface coated with modified montmorillonite and the coating material, and perform compression molding to obtain the polystyrene board with flame retardant properties, which is referred to as polystyrene board I.

[0055] Example 2

[0056] This embodiment provides a polystyrene board with flame retardant properties, which includes the following components in parts by weight: 100 parts of expandable polystyrene, 60 parts of thermosetting resin, 2 parts of sulfuric acid, 4 parts of hexadecyltrimethylammonium bromide modified montmorillonite and 40 parts of coating material;

[0057] The coating material is compounded by diatomaceous earth-based flame retardant, silica aerogel and nanocellulose in a mass ratio of 3.5:8:0.3; the average particle size of the silica aerogel is 15.0 μm;

[0058] Wherein, the diatomaceous earth-based flame retardant is diatomaceous earth modified by gemini quaternary ammonium salt;

[0059] The thermosetting resin is compounded by phenolic resin and epoxy resin in a mass ratio of 6:1.

[0060] The preparation method of the diatomaceous earth-based flame retardant comprises the following steps:

[0061] Step A, preparation of gemini quaternary ammonium salt

[0062] In a three-necked flask equipped with a reflux condenser, a certain amount of anhydrous ethanol was added, triethylamine and 1,5-dibromopentane were added in a mass ratio of 1.14:1 (molar ratio of 2.3:1), and quaternization reaction was carried out at 85°C for 5 hours; magnetic stirring was performed during the quaternization reaction, and the stirring speed was 150rpm. After the quaternization reaction, the mixture was cooled to room temperature to obtain a colorless transparent liquid, and the solvent was removed by reduced pressure distillation at 60°C; then the mixture was rinsed three times with ethyl acetate and acetone in a volume ratio of 1:1, and a white solid was obtained by suction filtration, which was vacuum dried at 50°C to obtain the target product;

[0063] The above target product contains quaternary ammonium salt N + The characteristic peaks of tertiary amine indicate that the tertiary amine has undergone quaternization reaction; that is, the target product obtained is a gemini quaternary ammonium salt, and its structural formula is: .

[0064] Step B: Preparation of Gemini Quaternary Ammonium Salt Modified Diatomaceous Earth

[0065] The diatomite and deionized water were mixed, heated in a water bath at 80°C and mechanically stirred until uniformly dispersed, to obtain a diatomite suspension with a mass concentration of 50 g / L. The above-prepared gemini quaternary ammonium salt and deionized water were weighed, and fully stirred until completely dissolved to obtain a gemini quaternary ammonium salt solution with a mass concentration of 60 g / L. The above gemini quaternary ammonium salt solution was mixed with the diatomite suspension to obtain a mixed suspension, mechanically stirred at 85°C for 3h, and then the mixed suspension was centrifuged and washed 3 times with deionized water, placed in a drying oven and dried at 80°C to constant weight, and ground to 300 mesh to obtain gemini quaternary ammonium salt modified diatomite.

[0066] Wherein, the mass ratio of the gemini quaternary ammonium salt to diatomaceous earth in the mixed suspension is 1.4:3.

[0067] In this embodiment, the phenolic resin selected is SP1068 phenolic resin; the epoxy resin selected is DER6508 epoxy resin;

[0068] This embodiment also provides a method for preparing the polystyrene board having flame retardancy, and the preparation method comprises the following steps:

[0069] Step 1: Pre-expand expandable polystyrene with steam to obtain a density of 25kg / m 3 Pre-fermented pellets;

[0070] Step 2: Add thermosetting resin and sulfuric acid to the pre-expanded granular material and mix evenly, then mix at 70°C for 15 minutes, add hexadecyltrimethylammonium bromide modified montmorillonite and mix evenly, then add the coating material to obtain the pre-expanded granular material with the surface coated with modified montmorillonite and the coating material, and perform compression molding to obtain the polystyrene board with flame retardant properties, which is recorded as polystyrene board II.

[0071] Example 3

[0072] This embodiment provides a polystyrene board with flame retardant properties, which includes the following components in parts by weight: 95 parts of expandable polystyrene, 53 parts of thermosetting resin, 2.2 parts of phosphoric acid, 3 parts of hexadecyltrimethylammonium bromide modified montmorillonite and 35 parts of coating material;

[0073] The coating material is compounded by a diatomaceous earth-based flame retardant, silica aerogel and nanocellulose in a mass ratio of 4:6:0.2; the average particle size of the silica aerogel is 10.0 μm;

[0074] Wherein, the diatomaceous earth-based flame retardant is diatomaceous earth modified by gemini quaternary ammonium salt;

[0075] The thermosetting resin is compounded by phenolic resin and epoxy resin in a mass ratio of 5:1.

[0076] The preparation method of the diatomaceous earth-based flame retardant comprises the following steps:

[0077] Step A, preparation of gemini quaternary ammonium salt

[0078] In a three-necked flask equipped with a reflux condenser, a certain amount of anhydrous ethanol was added, triethylamine and 1,5-dibromopentane were added in a mass ratio of 1.08:1 (molar ratio of 2.1:1), and a quaternization reaction was carried out at 83°C for 5.5 hours; magnetic stirring was performed during the quaternization reaction at a stirring speed of 150rpm. After the quaternization reaction, the mixture was cooled to room temperature to obtain a colorless transparent liquid, and the solvent was removed by reduced pressure distillation at 60°C; then the mixture was rinsed three times with ethyl acetate and acetone in a volume ratio of 1:1, and a white solid was obtained by suction filtration, which was vacuum dried at 50°C to obtain the target product;

[0079] The above target product contains quaternary ammonium salt N +The characteristic peaks of tertiary amine indicate that the tertiary amine has undergone quaternization reaction; that is, the target product obtained is a gemini quaternary ammonium salt, and its structural formula is: .

[0080] Step B: Preparation of Gemini Quaternary Ammonium Salt Modified Diatomaceous Earth

[0081] The diatomite and deionized water were mixed, heated in a water bath at 80°C and mechanically stirred until uniformly dispersed, to obtain a diatomite suspension with a mass concentration of 60 g / L. The above-prepared gemini quaternary ammonium salt and deionized water were weighed, and fully stirred until completely dissolved to obtain a gemini quaternary ammonium salt solution with a mass concentration of 50 g / L. The above gemini quaternary ammonium salt solution was mixed with the diatomite suspension to obtain a mixed suspension, mechanically stirred at 82°C for 3.5 hours, and then the mixed suspension was centrifuged and washed 3 times with deionized water, placed in a drying oven and dried at 80°C to constant weight, and ground to 300 meshes to obtain gemini quaternary ammonium salt modified diatomite.

[0082] Wherein, the mass ratio of the gemini quaternary ammonium salt to diatomaceous earth in the mixed suspension is 1.2:3.

[0083] In this embodiment, the phenolic resin selected is SP1068 phenolic resin; the epoxy resin selected is DER6508 epoxy resin;

[0084] This embodiment also provides a method for preparing the polystyrene board having flame retardancy, and the preparation method comprises the following steps:

[0085] Step 1: Pre-expand expandable polystyrene with steam to obtain a density of 22kg / m 3 Pre-fermented pellets;

[0086] Step 2: Add thermosetting resin and phosphoric acid to the pre-expanded granular material and mix evenly, then mix at 75°C for 12 minutes, add hexadecyltrimethylammonium bromide to modify the montmorillonite and mix evenly, then add the coating material to obtain the pre-expanded granular material with the surface coated with modified montmorillonite and the coating material, and perform compression molding to obtain the polystyrene board with flame retardant properties, which is recorded as polystyrene board III.

[0087] Comparative Example 1

[0088] Comparative Example 1 provides a polystyrene board with flame retardant properties. The raw materials and preparation method of the polystyrene board with flame retardant properties in this comparative example are basically the same as those in Example 3, except that: in terms of raw materials, the flame retardant selected is diatomaceous earth, and no organic modified montmorillonite is added, and the types and amounts of other raw materials are the same as those in Example 3;

[0089] In the preparation method, the original "gemini quaternary ammonium salt modified diatomaceous earth" was replaced by "diatomaceous earth", and no organic modified montmorillonite was added. The other preparation parameters were the same as those in Example 3, and the obtained product was recorded as polystyrene board pair I.

[0090] Effect Example 1

[0091] Determine the thermal conductivity of different products according to GB / T10294-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Insulating Materials - Guarded Hot Plate Method";

[0092] Determine the fire rating of different products according to GB8624-2019 "Classification of Combustion Performance of Building Materials and Products";

[0093] The compressive strength of different products is measured in accordance with GB / T 10801.1-2021 "Molded polystyrene foam (EPS) for thermal insulation".

[0094] The tensile strength is measured in accordance with JG / T 536-2017 "Thermosetting composite polystyrene foam insulation board".

[0095] The specific measurement results are shown in Table 1.

[0096] Table 1

[0097]

[0098] It can be seen from the data in Table 1 that, compared with the polystyrene board to which diatomaceous earth is added as a flame retardant and no organic modified montmorillonite is added, the thermal conductivity of the polystyrene board provided by the present invention is significantly reduced and the fire resistance level is improved.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A polystyrene board with flame retardant properties, characterized in that: The invention comprises the following components in parts by weight: 90 to 100 parts of expandable polystyrene, 50 to 60 parts of thermosetting resin, 1.2 to 2.2 parts of curing agent, 2 to 4 parts of organic modified montmorillonite and 30 to 40 parts of coating material; The coating material comprises a diatomaceous earth-based flame retardant, a silica aerogel and nanocellulose; wherein the mass ratio of the diatomaceous earth-based flame retardant, the silica aerogel and the nanocellulose in the coating material is 3-4:6-12:0.2-0.4; Wherein, the organic modified montmorillonite is hexadecyltrimethylammonium bromide modified montmorillonite; The diatomaceous earth-based flame retardant is diatomaceous earth modified by gemini quaternary ammonium salt; The structural formula of the gemini quaternary ammonium salt is: 。 2. The flame retardant polystyrene board according to claim 1, characterized in that: The preparation method of the gemini quaternary ammonium salt comprises the following steps: reacting 1,5-dibromopentane and triethylamine at 81° C. to 85° C. for 5 h to 6 h to obtain the gemini quaternary ammonium salt.

3. The flame retardant polystyrene board according to claim 1 or 2, characterized in that: The preparation method of the gemini quaternary ammonium salt modified diatomite comprises the following steps: mixing a diatomite suspension with a gemini quaternary ammonium salt solution, reacting at 81° C. to 85° C. for 3 h to 4 h to obtain the gemini quaternary ammonium salt modified diatomite.

4. The flame retardant polystyrene board according to claim 1, characterized in that: The silica aerogel is a micron-sized silica aerogel.

5. The flame retardant polystyrene board according to claim 1, characterized in that: The thermosetting resin includes phenolic resin and epoxy resin in a mass ratio of 6:1 to 4:

1.

6. The flame retardant polystyrene board according to claim 1, characterized in that: The curing agent includes at least one of phosphoric acid, sulfuric acid, phthalic anhydride or maleic anhydride.

7. The method for preparing a polystyrene board having flame retardancy according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: Step 1, pre-expanding expandable polystyrene to obtain pre-expanded granular material; Step 2: Add the thermosetting resin and curing agent to the pre-expanded granular material and mix them evenly, then add the organic modified montmorillonite and the coating material in sequence, and perform compression molding to obtain the polystyrene board with flame retardant properties.

8. Use of the flame retardant polystyrene board according to any one of claims 1 to 6 or the flame retardant polystyrene board prepared according to claim 7 in building walls.

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